There are various ways to define attention vectors. Specifically, in our situation, it is a local optimization issue, where the general attention vector can achieve a proper performance without huge additional computing cost [1]}. Hence, we utilize the general attention style to compute the attention vector \(t\)  as follows:
\(\begin{aligned}\text{f}({z_u},A) = z_u^T{W_t}A,\end{aligned}\) 
\(\begin{aligned}{t_u} = \text{align}({z_u},A) = \frac{{\exp (f({z_u},A))}}{{\sum \nolimits _\text{A} {\exp (f({z_u},A))} }},\end{aligned}\) 
